General question about building planning without a development plan

Hi everyone,

I have a very general question: If you want to buy a property with a large plot of land or just a plot of land and there is no development plan, how can you find out as quickly as possible whether building is allowed there? Can an architect assess this with high probability, or does it only work with a building inquiry? The latter can take some time, and the property listed for sale may already be sold by then...

I would be glad if someone here could help me gain a better understanding.

Thank you very much.

P.S.:
I hope I have posted my question in the right subforum.

If you want to buy a property with a large plot of land or just a plot and there is no development plan there, how can you find out as quickly as possible whether building is allowed there? Can an architect assess something like that correctly with a high probability,

Tomorrow is Monday, then you can call someone at the building authority again. Many municipalities also have development plans available online. An architect has access to the same sources as you – he can only read the development plan faster and more thoroughly. Many experienced laypeople here can also interpret clues.

Thank you very much for your help. That is also how I understood it in the case of the existence of a development plan. However, my concern is a situation in which no development plan exists. Then §34 should apply, right? If correct, then the above question would refer exactly to this case. If I could be helped with this, I would be very pleased.

If it is a 34 zoning area, then the corresponding regulations apply. The extent of structural use (floor area ratio) can be estimated using Goo** Maps and geoportals, the number of floors based on the surrounding buildings. Additionally, the usual setback areas. This allows for a fairly good estimation of what is possible.

Great, accordingly one should be able to rely well on an assessment from the architect. Since, as I said, I would like to build a bit more understanding, I have two follow-up questions: 1. How do I know if it is an area according to [§ 34]? Is that automatically the case if there is no development plan? 2. For many plots with property, often only the plot in the hinterland (is that how you say it?) is developable, since on the street side, left and right, there are already other properties. That certainly makes the whole thing a bit more complicated. How reliable is the assessment of an architect then?

Unplanned inner areas apply only within towns, whereby there can also be areas that are referred to as outer areas within the inner area. The boundary to the outer area runs along the development. A parcel of land can, for example, also partly lie in the outer area and thus be only partially buildable. Geoportals or cadastral excerpts can help with this. Development in the second row can be rejected under certain circumstances.